Apparatus and method for submergible self-retaining mandibular distractor

ABSTRACT

An apparatus and method for submergible self-retaining distraction osteogenesis is provided. Distraction osteogenesis devices are submerged below a layer of tissue and/or skin layers and are activated based upon maximum pressures, rather than constant activation rates. Distraction osteogenesis devices are also self-retaining in that the force in displacing bone segments is transferred substantially through metal plates, rather than screws or fixation points. In particular, zygomatic, alveolar and mandibular distraction osteogenesis devices are provided. The zygomatic and alveolar distraction osteogenesis devices include a submergible first and second metal plate along with a threaded rod. The zygomatic and alveolar distraction osteogenesis devices are activated using a cannula, torque wrench adapter and torque wrench. The mandibular distraction osteogenesis device includes a palate expander having a plurality of rods used in coupling first and second self-retaining U-shaped plates. The mandibular distraction osteogenesis device is activated using an allen wrench. In order to allow for maximum bone growth and/or distraction, a maximum pressure between bone segments is applied by a torque or allen wrench.

This application is a divisional of Ser. No. 08/732,064, filed Oct. 16,1996, now U.S. Pat. No. 5,769,850.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to distraction osteogenesis.

2. Description of the Related Art

Distraction osteogenesis refers to a technique for growing bone orosteogenesis material, as well as soft tissue, by separating two bonesegments. Generally, an osteotomy, such as a Lefort III osteotomy, isperformed which partitions a bone into two bone segments. Externaldistraction osteogenesis devices are then attached to the bone segmentsthrough soft tissue or a skin layer. These external distractionosteogenesis devices may include rods and rings or other cumbersomemetal components. The distraction osteogenesis devices form a gapbetween the bone segments by exerting pressure between the bonesegments. As the gap between the bone segments widens, the body's ownnatural healing capacity fills the void with new bone and adjacent softtissue. Once the desired bone formation is achieved, the area is allowedto heal and consolidate. Often, the distraction osteogenesis device isthen removed.

An example of a distraction osteogenesis device is an llizarovdistractor. Typically, an llizarov distractor is used in lengtheningindividuals' limbs, such as a leg. In this application, an llizarovdistractor may include external metal rings which are then secured totwo bone segments in a leg. These metal rings are then attached by a rodassembly which may be used to form a gap between the two bone segmentsand thus allow for the formation of new bone. A description of anllizarov distractor may be found in U.S. Pat. No. 4,615,338, issued tollizarov, et al. on Oct. 7, 1986 and entitled "AutomaticCompression--Distraction Apparatus."

Distraction osteogenesis devices may also be used in growing bone in thecraniofacial region of small children. Often, distraction osteogenesisdevices are used on small children who are missing bone due to birthabnormalities or accidents. While distraction osteogenesis devices areoften used on children, distraction osteogenesis devices may be used onadults and animals as well.

A number of problems are encountered in using present distractionosteogenesis devices. First, distraction osteogenesis devices aregenerally external, which may cause a number of problems orcomplications. Often, cumbersome metal rods and rings located externalto an individual's skin are used to distract or separate bone segments.Individuals, and in particular small children, may fall and injurethemselves on the protruding metal edges. Further, small children maycomplicate the distraction osteogenesis procedure by improperlyadjusting the osteogenesis distraction device.

The distraction osteogenesis device may require multiple entry points toan individual'skin and thus may create multiple scars. Distractionosteogenesis devices requiring multiple entry points may also increasethe likelihood of infection due to the multiple openings in theindividual's skin. Also, individuals undergoing the distractionosteogenesis procedure have to cope with an external device which is notcosmetically appealing.

A second problem encountered with distraction osteogenesis devicesregards customizing devices for individuals. Generally, a distractionosteogenesis device used for one individual would not be suitable foranother. In distraction osteogenesis devices used in the craniofacialarea, distraction osteogenesis devices must be measured to fit specificsurface areas of craniofacial bones. Also, individuals may havedifferent amounts of bone caused by different types of birthabnormalities or accidents, thus requiring customized distractionosteogenesis devices due to limited bone.

Third, distraction osteogenesis devices are attached to bone segments insuch a way that the point of fixation to the bone transfers force duringactivation. For example, a distraction osteogenesis device may beattached to a bone segment by a bone screw or rod which transfers asubstantial amount of force during activation or when the distractionosteogenesis device is exerting pressure between the bone segments. Byhaving the bone screw transfer a substantial amount of the force duringactivation, the distraction osteogenesis device may be dislodged fromthe bone.

Fourth, distraction osteogenesis devices are activated using constantrates which do not reflect the individual's healing abilities.Regardless of the age or condition of the individual, distractionosteogenesis devices are activated by widening the gap between bonesegments 0.25-0.50 mm four times per day. This conventional activationrate results in bone growth as low as 20 mm in 20 days. Accordingly, anindividual may have to be under constant medical supervision for up to20 days. An individual could be an outpatient, but would need to returnto the hospital four times per day for adjustments. Present distractionosteogenesis device activation techniques do not take into account anindividual's ability to grow bone at a greater or lesser rate. By usingthis constant rate, bone may grow too quickly and lock the distractionosteogenesis device, or in the alternative, bone may grow too slowly,requiring a longer period of time that the distraction osteogenesisdevice is necessary.

Therefore, it is desirable to provide a distraction osteogenesis devicewhich is submergible, or beneath an individual's skin or soft tissue.The distraction osteogenesis device then could be permanently positionedwithin an individual, thereby eliminating the need for surgery inremoving the device, including the associated risks and costs. Thedistraction osteogenesis device then would be more cosmeticallyappealing and reduce the likelihood of infection, injury and/or scaring.Further, it is desirable to have a distraction osteogenesis device whichdoes not have to be customized for each individual. Manufacturing andmedical costs would then be substantially reduced by using a standarddistraction osteogenesis device and method, rather than customizingdistraction osteogenesis devices and methods for each individual. Thedistraction osteogenesis device also should be affixed to bone in such away that a substantial amount of the force used in activation is nottransferred through a fastening device (i.e., screw, pin or rod).Finally, the distraction osteogenesis device should be activated at arate which optimizes bone growth.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, an apparatus isprovided for distracting a first bone segment from a second bonesegment. The apparatus comprises a first implantable plate for couplingthe first bone segment and a second implantable plate for coupling thesecond bone segment. Submergible means is coupled to the first plate andthe second plate which positions the first plate a distance from thesecond plate responsive to a force.

According to another aspect of the present invention, the submergiblemeans includes a threaded rod portion.

According to another aspect of the present invention, the submergiblemeans includes a palate expander having a plurality of rods.

According to another aspect of the present invention, the apparatusincludes activating means for transferring a force to the submergiblemeans.

According to another aspect of the present invention, the activatingmeans includes a cannula, a torque wrench adapter and a torque wrench.

According to another aspect of the present invention, the apparatusincludes means for removing the activating means.

According to another aspect of the present invention, the first andsecond plates transfer a substantial amount of the force.

According to another aspect of the present invention, the activatingmeans transfers a force generating a maximum pressure in order toachieve a maximum distance.

According to another aspect of the present invention; a submergibledevice for distracting a first segment of the zygoma from a secondsegment of the zygoma to allow for bone generation is provided. Thesubmergible device includes an implantable rod having a threadedportion, a base and an activation end. An implantable L-shaped member iscoupled to the first segment of the zygoma and has a protruding portionfor inserting the threaded portion of the rod. An implantable curvedmetal member is coupled to the second segment of the zygoma and has anopening for positioning the rod activation end. The rod base transfers aforce against the curved member, creating a distance between the firstand second zygoma segments responsive to a force.

According to another aspect of the present invention, a method forforming zygomatic bone is provided. The method includes the steps of (a)cutting the zygoma into first and second segments; (b) forming a firstnotch in a first segment; (c) forming a first notch in a second segment;(d) securing a first plate under a layer of tissue to the notch in thefirst segment; (e) coupling a rod to the first plate; (f) securing asecond plate under the layer of tissue to the notch in the secondsegment; and (g) exerting a force on the rod in order to displace thefirst segment of zygoma from the second segment of zygoma.

According to another aspect of the present invention, a submergibledevice for distracting a first segment of alveolus from a second segmentof alveolus to allow for bone generation is provided. The submergibledevice comprises a rod having a threaded portion, including an end, abase and an activation end. A first member is coupled to the firstsegment of alveolus and has an opening for inserting the rod end. Asecond member is coupled to the second segment of alveolus and has anopening for positioning the threaded portion of the rod. The rodtransfers a force against the second member, creating a distance betweenthe first and second alveolus segments.

According to another aspect of the present invention, a method forforming alveolar bone is provided. The method includes the steps of: (a)cutting the alveolus into first and second segments; (b) securing afirst plate to the first segment of alveolus; (c) forming an opening inthe second segment of alveolus; (d) securing a second transport plate tothe second segment of alveolus; (e) inserting a rod into the opening ofthe second segment of alveolus and through the second plate opening tothe first plate; and (f) exerting a force on the rod to displace thefirst segment of alveolus from the second segment of alveolus.

According to another aspect of the present invention, a submergibledevice for distracting a first segment of mandible from a second segmentof mandible to allow for bone generation is also provided. Thesubmergible device comprises a first U-shaped member which is coupled tothe first segment of mandible. A second U-shaped metal member is coupledto a second segment of mandible. A palate expander having a first pairof rods and second pair of rods is coupled to the first U-shaped memberand the second U-shaped member, respectively. The palate expandertransfers a force against the first and second U-shaped members,creating a distance between the first and second mandible segments.

According to another aspect of the present invention, a method forforming mandibular bone is provided. The method comprises the steps of:(a) cutting the mandible into first and second segments; (b) coupling afirst member to a palate expander; (c) coupling a second member to thepalate expander; (d) positioning the palate expander between the firstand second segment; (e) securing the first and second members to thefirst and second segments of mandible; and (f) activating the palateexpander in order to displace the first segment of mandible from thesecond segment of mandible.

Other aspects and advantages of the present invention can be seen uponreview of the figures, the detailed description, and the claims whichfollow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a distraction osteogenesis device according to thepresent invention.

FIG. 2 illustrates a distraction osteogenesis apparatus, including aninserted distraction osteogenesis device, a cannula, a torque wrenchadapter and torque wrench according to the present invention.

FIG. 3 illustrates a bottom view of a distraction osteogenesis devicehaving self-retaining plates, a cannula and torque wrench adapteraccording to the present invention.

FIG. 4 illustrates a distraction osteogenesis device after activationand removal of a cannula according to the present invention.

FIGS. 5a-c illustrate a distraction osteogenesis apparatus having aposterior cranial activation according to the present invention.

FIG. 6 illustrates a cannula removal device according to the presentinvention.

FIGS. 7-9 illustrate the steps for inserting a distraction osteogenesisdevice according to the present invention.

FIG. 10 illustrates an alveolar distraction osteogenesis apparatus,including an alveolar distraction device, cannula, torque wrench adapterand torque wrench according to the present invention.

FIGS. 11a-b illustrate an alveolar distraction osteogenesis rod, cannulaand torque wrench adapter according to the present invention.

FIGS. 12a-c illustrate alveolar distraction osteogenesis platesaccording to the present invention.

FIGS. 13a-b illustrate the steps of inserting an alveolar distractionosteogenesis device according to the present invention.

FIG. 14a illustrates activating an inserted alveolar distractionosteogenesis device according to the present invention.

FIG. 14b illustrates an inserted activated alveolar distractionosteogenesis device according to the present invention.

FIG. 15 illustrates a mandibular distraction osteogenesis deviceaccording to the present invention.

FIG. 16a illustrates an inserted mandibular distraction osteogenesisdevice in an activated position according to the present invention.

FIG. 16b illustrates an inserted mandibular distraction osteogenesisdevice in an activated position and an allen wrench according to thepresent invention.

FIG. 17a illustrates an inserted mandibular distraction osteogenesisdevice in a non-activated position according to the present invention.

FIG. 17b illustrates a medial view of a mandibular distractionosteogenesis device having self-retaining flanges according to thepresent invention.

FIG. 18 illustrates an inserted mandibular distraction osteogenesisdevice in a non-activated position according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

I. Distraction Osteogenesis Apparatus

FIG. 1 illustrates distraction osteogenesis device 10 according to thepresent invention. In a preferred embodiment, distraction osteogenesisdevice 10 is constructed from titanium. In alternate embodiments,stainless steel or other hardened material may be used. Distractionosteogenesis device 10 is implantable or is inserted under anindividual's or animal's soft tissue and/or skin layer. In anembodiment, the distraction osteogenesis device is a LeFort IIIdistractor for the zygoma.

Distraction osteogenesis device 10 includes a rod 11, zygoma posteriorplate 16 and zygoma anterior plate 15. Rod 11 includes a threadedportion 12, base 13 and activation end 14. In an embodiment, threadedportion 12 has a diameter of approximately 2.5 mm and a pitch of 0.45 mmper revolution and base 13 has a diameter of approximately 0.1875inches. In an embodiment, the diameter of activation end 14 isapproximately 0.0932 inches. Activation end 14 is used in activatingdistraction osteogenesis device 10. Bone segments affixed toosteogenesis device 10 are separated responsive to a force which createsa pressure between the bone segments. Activation end 14 includes atapered bayonet portion 14a having an angle 21 from normal. In anembodiment, angle 21 is approximately 3°.

Zygoma anterior plate 15 has a plurality of openings. Opening 18 has adiameter 24. In an embodiment, diameter 24 is approximately 0.094inches. Opening 24 is used to position activation end 14 of rod 10.Openings 19 are used for inserting screws 20 which affixes the zygomaanterior plate 15 to the zygoma, as illustrated in FIGS. 2-4. While twoopenings 19 are illustrated, other embodiments may include a greater orlesser number of openings for fixing the zygoma anterior plate 15,depending upon the positioning of the zygoma anterior plate 15 and theamount of zygoma available. As described in detail below, the zygomaanterior plate 15 is formed in such a way that during activation, asubstantial amount of pressure is exerted against, or transferredthrough, the zygoma anterior plate 15 and not transferred through screws20. Specifically, the activation force is transferred from rod base 13against platform 29. Screws 20 are used primarily for fastening thezygoma anterior plate 15 and do not transfer a substantial amount offorce during activation. In an embodiment, screws 20 are available fromPfizer Pharmaceuticals, Inc., located at Valley Lab, Inc., P.O. Box9015, 5920 Longbow Drive, Boulder, Colo. 80301-9015. In an embodiment,screws 20 have a diameter of between approximately 1.5 mm and 2.0 mm. Inan embodiment, the diameters of screws 20 are sized such that they areslightly larger than openings 19 in order to fasten plates 15 and 16 byself-threading the openings 19. In another embodiment, the diameters ofscrews 20 are sized such that there is slight movement between platesand bone. Zygoma anterior plate 15 is formed in order to be used on amajority of individuals, regardless of size or age.

Similarly, the zygoma posterior plate 16 has a plurality of openings 19.Threaded opening 17 is used to insert threaded portion 12 of rod 10.Openings 19 are used to insert screws 20 for positioning the zygomaposterior plate 16. The zygoma posterior plate 16 is formed in such away that a substantial portion of the force during activation istransferred through the plate and not the screws 20. Screws 20 are usedfor fastening the zygoma posterior plate 16 as illustrated in FIGS. 2-4.As above, the diameter of screws 20 is selected in order to self-threadopenings 19 or to allow slight movements between plate and bone. Thethreaded portion of opening 17 is 2.5 mm diameter at a 0.45 mm pitch.

Zygoma posterior plate 16 and zygoma anterior plate 15 is formed inorder to be used for most individuals, regardless of age or size. Inparticular, it was discovered during multiple clinical evaluations thatusing a distraction osteogenesis device 10 having a certain size andconfiguration enables a vast majority of individuals to use thedistraction osteogenesis device. Specifically, angle 23 was found to bebetween approximately 65° to 75° and angle 22 to be betweenapproximately 15° and 25°. In a preferred embodiment, angle 22 isapproximately 20°. The distance 28 was found to be between 0.1 and 0.3inches. In the preferred embodiment, distance 28 is 0.2 inches.

FIGS. 2-4 illustrate an inserted and activated distraction osteogenesisdevice 10. As can be seen from FIG. 2, zygoma anterior plate 15 ispositioned by screw 20 to zygoma segment 35 and zygoma posterior plate16 is positioned to zygoma segment 36 by screw 20. Activation, orseparating bone segments 36 and 35, is accomplished by cannula 31,adapter 32 and torque wrench 30. Torque wrench 30, adapter 32 andcannula 31 are also illustrated in FIG. 10. Adapter 32 includes a rod32a having a tapered bayonet end 32b for fitting rod activation end 14a.FIG. 10 illustrates a cannula length considerably shorter than the oneillustrated in FIGS. 2-4. Cannula 31 is first positioned over rod 11, inparticular activation end 14. Adapter 32 is then used to couple rod 11by inserting rod 32a into cannula 31. A hammer is then used to lodge thetapered end 32b of adapter 32 into activation end 14 of rod 11. Torquewrench 30 is then coupled to adapter interface 32c. In an embodiment,the torque wrench 30 may be available from Interpore International, 181Technology Drive, Irvine, Calif. 92618.

A predetermined torque setting corresponding to a distraction pressurein then set on torque wrench 30. Torque wrench 30 is then rotated inorder to create a force which separates plates 16 and 15 and thus bonesegments 36 and 35. The torque wrench 30 setting corresponds to apressure exerted by distraction osteogenesis device 10. The relationshipbetween a torque wrench 30 setting and exerted distraction osteogenesisdevice 10 pressure is determined before inserting device 10. Forexample, it was discovered during clinical evaluations that a 14 Newtoncm and 18 Newton cm torque wrench setting corresponds to 7 kg and 9 kgof pressure exerted by distraction osteogenesis device 10. The amount oftorque applied is based upon the maximum pressure the bone segments canwithstand without breaking. This is observed after insertion and beforeclosing. Before the soft tissue or skin is sutured, distractionosteogenesis device 10 is activated until the bone segment appears tobend. This maximum torque setting is then used to maintain a maximumpressure between the bone segments. Throughout the distraction process,this maximum pressure is maintained rather than using conventionalactivation rates. This maximum pressure thus enables optimized bonegrowth.

FIG. 3 illustrates a bottom view of distraction osteogenesis device 10coupled to cannula 31 and adapter 32 for both the left and right sidezygoma.

FIG. 4 illustrates an activated, or distracted, distraction osteogenesisdevice 10 with the cannula 31 and adapter 32 removed. As can be seen,distraction osteogenesis device 10 may be submerged or implanted underan individual's tissue or skin layers. In particular, plate 16, plate 15and threaded port on 12 of rod 11 may be submerged under an individual'sskin. Further, it should be observed that the screws 20 are not used totransfer a substantial amount of the force from torque wrench 30 duringactivation. Screws 20 are used to position plates 16 and 15 and arepositioned substantially perpendicular to the force transferred alongrod 11. The plates 16 and 15 are self-retaining in the sense that asubstantial amount of the force is transferred through the plates,rather than the fixation points or screws. Thus, distractionosteogenesis device 10 is less likely to break away from bone. Further,more force may also be applied because the screws are not transferring asubstantial amount of force.

FIGS. 5a-c illustrate a method for inserting zygomatic distractionosteogenesis device 10 in a posterior procedure. Rather than activatingdistraction osteogenesis device 10 through an opening in the face, thezygomatic distraction device 10 may be activated posterior to, or fromthe back of, the cranium. FIG. 5a illustrates plate 16 fixed to zygomasegment 36 and plate 15 fixed to zygoma segment 35. In this embodiment,rod 10 would have a similar tapered end 14 at the end of threadedportion 12 for activation. The posteriorly directed activating rodemerges from the surgical incision without requiring a separate skinpenetration. FIG. 5a illustrates the cannula 31, torque wrench adapter32 and torque wrench 30. FIGS. 5b and 5c illustrate zygomaticdistraction osteogenesis device 10 without torque wrench 30 and from abottom view, respectively. This embodiment offers the advantage of notcreating facial scars.

FIG. 6 illustrates a cannula and rod removal device 44, according to thepresent invention. Cannula and rod removal device 44, along with allenwrench 40, is used to remove a cannula 31 and activation rod 32a afteractivation. Torque wrench interface adapter 32c, as illustrated in FIGS.2, 3 and 10, is removed before using the cannula and rod removal device44. Torque wrench adapter interface 32c is coupled to activation rod 32aby a set screw which may be loosened to remove adapter interface 32c.Cannula 31 is secured by clamp 42 by rotating allen wrench 40. After thecannula 31 is secured, the cannula can be removed by rotating knob 43and holding cylindrical portion 41, forcing a piston against activationrod 32a in cannula 31. The cannula 31 and rod 32a are then dislodged andmay be removed.

II. Distraction Osteogenesis Device Insertion and Activation Method

FIGS. 7-9 illustrate preparing bone segments, for example the zygomabone, for inserting distraction osteogenesis device 10 according to thepresent invention. FIGS. 2-4 illustrate activating the inserteddistraction osteogenesis device 10, while FIG. 6 illustrates removing acannula 31 and rod 32a.

In an embodiment, a computed tomography scan of the area for distractionosteogenesis may be obtained. Distraction osteogenesis device 10 maythen be manufactured using the information from computed tomography. Forexample, the length of rod 11 may be determined from this imaginginformation. Moreover, the amount of bone available and/or number ofscrews used to affix the distraction osteogenesis device, may beestimated based upon the image information. In the preferred embodiment,a customized distraction osteogenesis device is not used and distractionosteogenesis device 10 having the above-described configuration and sizesuitable for a majority of individuals is used.

An osteotomy is then performed to create two bone segments 35 and 36which will be distracted in order to form new bone. FIG. 7 illustratescreating an incision 54 in the zygoma. Indent 51 and 52 are then formedin bone segment 36 an bone segment 35, respectively, by drill 56. As canbe seen, notch 51 is slightly larger than notch 52.

FIG. 8 illustrates forming a groove 53 for the curved portion 15a of thezygoma anterior plate 15. FIG. 9 illustrates drill 56 forming notch 51.

A zygoma posterior plate 16 is then inserted into indent 51 and fastenedto zygoma 36 by screws 20, as illustrated in FIG. 2. The number ofscrews used depends upon the bone available. Zygoma anterior plate 15 isthen inserted into indent 52 and groove 53 and fixed by screws 20. Inthe preferred embodiment, anterior plate 15 is inserted by wedgingplatform 29 into incision 54 or between notches 51 and 52. Anteriorplate 15 then is rotated to fit against zygoma bone 35. Likewise, thenumber of screws used depends upon the amount of bone available. Rod 11then may be inserted through openings 17 and 18. In particular, thethread portion of rod 11 is screwed into opening 17, while rod base 13is positioned against platform 29 of plate 15, allowing for tapered end14 to be inserted through opening 18. A cannula 31 and adapter 32 havingactivation rod 32a is then positioned, as illustrated in FIG. 2. Thecannula may be positioned over tapered end 14 by way of a thinpositioning rod. Torque wrench 30 is then screwed to adapter 32. Torquewrench 30 is then rotated to a predetermined torque settingcorresponding to a maximum pressure. Rather than using a constantactivation rate, the distraction osteogenesis device exerts a maximumpressure between zygoma segments 35 and 36. The pressure is monitoredthroughout the day and additional torque is applied in order to maintaina maximum pressure. This maximum pressure on the zygoma optimizes bonegrowth, requiring the shortest activation period possible. Usingconventional activation rates allows for the pressure to decrease from amaximum range. Maintaining a maximum pressure range on the bone segments35 and 36 allows for maximum bone growth and requires the minimalactivation period possible.

Cannula 31 and adapter 32 then may be removed, as described above andillustrated in FIG. 6.

Thus, distraction osteogenesis device 10 is submerged beneath softtissue and/or a layer of skin. The submerged distraction osteogenesisdevice reduces the likelihood of infection, as well as trauma, which maybe caused by a fall or improper activation of the distraction device.Further, the submergible distraction osteogenesis device is less likelyto leave scars and is more cosmetically appealing than externaldistraction osteogenesis devices. Using an activation rate based on anindividual's ability to generate bone allows for increased bone growth.During clinical studies, 20 mm of bone growth was obtained in two days,as opposed to using conventional activation rates requiring up to 25days.

Ill. Alveolar Distraction Osteogenesis Apparatus

FIG. 10 illustrates alveolar distraction osteogenesis apparatus 68. Thealveolar distraction osteogenesis apparatus 68 is used to form bone inthe alveolus which may be missing due to an accident or birthabnormality. Often, alveolus must be formed in order for dental implantsto be used. Similar to the distraction osteogenesis apparatusillustrated in FIGS. 1 and 2, the alveolar distraction osteogenesisapparatus 68 includes a torque wrench 30, adapter 32 and cannula 31.

The alveolar distraction osteogenesis apparatus 68 also includes analveolar distraction osteogenesis device 69. The alveolar distractionosteogenesis device 69 includes a rod 60 having base 61, activation end62 and end 60a. The alveolar distraction osteogenesis device 69 alsoincludes a transport bone segment plate 63 and stabilizing plate 64.Plates 63 and 64 may be secured by screws 66 and 65, respectively.

FIGS. 11a-b illustrate two embodiments of an alveolar distractionosteogenesis device 69 shown in FIG. 10. FIG. 11a illustrates anonsubmergible alveolar distraction osteogenesis device, while FIG. 11billustrates a submergible alveolar distraction osteogenesis device. Thenonsubmergible alveolar distraction osteogenesis device in FIG. 11aincludes rod 70, cannula 72 and adapter 73. Rod 70 includes base 71 andend 78. The submergible alveolar distraction osteogenesis device shownin FIG. 11 includes rod 74, cannula 76 and adapter 77. Rod 74 includesbase 75 and end 79. The nonsubmergible alveolar distraction osteogenesisdevice illustrated in FIG. 11a has a rod 70 with a base 71 which may bepositioned substantially above soft tissue and/or a skin layer, whilebase 75 of rod 74 is positioned below soft tissue and/or a skin layer.Finally, the alveolar distraction osteogenesis device illustrated inFIG. 11b has a diameter of approximately 1.6 mm and a pitch of 0.35 mmper revolution, while the alveolar distraction osteogenesis deviceillustrated in FIG. 11a has a diameter of approximately 2.0 mm and apitch of 0.4 mm per revolution.

FIGS. 12a-c illustrate the transport bone segment plate 63 andstabilizing plate 64 illustrated in FIG. 10. In an embodiment,stabilizing plate 64 consists of a titanium member having openings 81,82 and 83. In an embodiment, a greater or lesser amount of openings maybe used. Openings 82 and 83 are used to fix plate 64 to bone withinserted screws. Further, embodiments may not require plate 64 if thebone material is sufficiently hard. The titanium member may be bentapproximately 90° between openings 81 and 82, as seen in plate 64 ofFIG. 10, to fit the alveolus. In an embodiment, opening 83 is anapproximately 1 mm opening for positioning a rod, such as rod end 79shown in FIG. 11b.

In an embodiment, transport bone segment plate 63 also is a titaniummember having three openings 84, 85 and 86, as illustrated in FIGS.12b-c. In an embodiment, a greater or lesser amount of openings may beused. Openings 85 and 86 are used to fix transport bone segment plate 63to bone with inserted screws. In an embodiment, both plate 64 and 63 areavailable from Pfizer Pharmaceuticals, Inc., located at Valley Lab,Inc., P.O. Box 9015, 5920 Longbow Drive, Boulder, Colo. 80301-9015. Thescrews, such as screws 66 and 65, as shown in FIG. 10, are alsoavailable from Pfizer Pharmaceuticals, Inc. In an embodiment, thediameter of washer-shaped member 87 surrounding opening 84 isapproximately 0.175 inches, while openings at 85 and 86 areapproximately 1.0 mm. In an embodiment, the width of the washer-shapedmember 87 is approximately 5 mm. The threaded portion of opening 84 hasa diameter of approximately 2 mm and a pitch of 0.4 mm per revolutionfor rod 70 and approximately 1.6 mm and a pitch of 0.35 mm perrevolution for rod 74. Threaded opening 84 is used to position rod 60.As with plate 64, transport bone segment plate 63 may be bentapproximately 90° between openings 85 and 84, as seen in transport bonesegment plate 63 of FIG. 10, to fit the alveolus.

As with the zygoma distraction described above, the alveolar distractionosteogenesis device may be implanted, and is thus submergible, beneath alayer of soft tissue.

Thus, the alveolar distraction osteogenesis device is less likely toscar and is more cosmetically appealing and comfortable than externaldistraction osteogenesis devices. A submerged alveolar distractionosteogenesis device is less likely to become infected than externaldevices. Also, the fixation points, in particular screws, which fix theplates to bone do not transfer a Substantial amount of force duringactivation. The screws are used to fix the plates and are insertedsubstantially perpendicular to the pressure separating the bonesegments. The alveolar distraction osteogenesis device may also beactivated using a maximum pressure, rather than at conventional constantactivation rates, as described above.

IV. Alveolar Distraction Osteogenesis Device Inserting and ActivatingMethod

FIGS. 13a-b illustrate a surgical view of an osteotomy and an insertedalveolar distraction osteogenesis device according to the presentinvention. Specifically, FIGS. 13a-illustrate a rod 60 inserted intostabilizing plate 64 and transport bone segment plate 63.

After determining the size of rod 60, an osteotomy is performed on thealveolus to form upper alveolus segment 88 and lower alveolus segment89. An opening 100 is then drilled into the lower alveolus segment 89.In an embodiment, an approximately 2 mm wide opening is formed.Stabilizing plate 64 is the positioned on the upper alveolus segment 88,while bone transport segment plate 63 is positioned on the loweralveolus segment. Bone screws then may be positioned through openings81, 82, 85 and 86 to fix the plates 63 and 64 to respective alveolussegments. FIGS. 13a-b illustrate a plate 64 without a screw in opening81. Rod 60 is then inserted into opening 100 through lower alveolussegment 89 and through opening 84 of plate 63. Rod end 60a is thenpositioned in opening 83 of plate 64.

As described in regard to the zygomatic distraction osteogenesis deviceabove, the alveolar distraction osteogenesis device may be activatedusing a torque wrench 30 and adapter 32, as illustrated in FIG. 14a. Asdescribed above, a maximum pressure may be exerted between upperalveolus 88 and lower alveolus 89 by setting the torque wrench to apredetermined setting. Thus, a relatively constant maximum pressure maybe obtained, ensuring optimal bone growth.

FIG. 14b illustrates a submerged alveolar distraction osteogenesisdevice in which only base 61 of rod 60 is visible. In an embodiment,base 61 may be used to position a temporary dental prosthesis. Thus, thealveolar distraction device is implanted and has a more cosmeticallyappealing appearance.

V. Mandibular Distraction Osteogenesis Device

FIG. 15 illustrates a mandibular distraction osteogenesis device 93according to the present invention. Mandibular distraction osteogenesisdevice 93 includes a palate expander 90, along with self-retainingplates 91 and 92, as seen in FIGS. 15-18. In an embodiment, distractionosteogenesis device 93 is constructed from stainless steel. In anembodiment, the palate expander 90 is a Lariat® palate expanderavailable from Easy Access Orthodontics, located at 2701 LaPaz Road,#236, Mission Viejo, Calif. 92691. The palate expander 90 includes twoextending components 90a and 90b which extend responsive to applying atorque at allen wrench opening 101 in palate expander 90. FIGS. 16a-billustrate a mandibular extraction device 93 in an activated position.Allen wrench 102 is inserted into allen wrench opening 101. A torquethen expands extracting components 90a and 90b. Extending components 90aand 90b are coupled to respective pairs of rods 94 and 95, as seen inFIG. 16b. The pairs of rods 94 and 95 are then used to couple toself-retaining plates 92 and 91. Self-retaining plates 91 and 92 areformed in a U-shaped manner having a plurality of openings, as seen inFIGS. 17a-b. Self-retaining plates 91 and 92 have flanges for grippingbone segments. Openings in plates 91 and 92 are also used to fasten theself-retaining plates 91 and 92 to mandible bone segments by screws. Forexample, screw 115 is used to fasten self-retaining plate 92, as shownin FIG. 18.

As with the distraction osteogenesis devices described above,submergible mandibular distraction osteogenesis device 93 has plateswhich transfer a substantial amount of pressure between bone segmentsrather than through fixation points. As extracting components 90b and90a move responsive to a torque being applied, force transfers throughself-retaining plates 91 and 92 and not through the screws used tofasten plates 91 and 92 to the mandible. Specifically, pressure isexerted at platforms 91a and 92a of plates 91 and 92, respectively, asshown in FIGS. 16a and 17a.

VI. Mandibular Distraction Osteogenesis Device Insertion and ActivationMethod

As described above with respect to the other distraction osteogenesisdevices, a computed tomography scan of a mandible may be obtained beforeinsertion and activation in order to determine the amount of boneavailable. An osteotomy is then performed in order to create mandibularbone segment 110 and mandibular bone segment 120, as seen in FIG. 16b.Self-retaining plates 91 and 92 are then positioned on pairs of rods 94and 95 by inserting the rods through openings in protruding edges 98 and99, respectively, of plates 92 and 91, as seen in FIGS. 17b and 18.Mandibular distraction osteogenesis device 93, including palate expander90 which is coupled to self-retaining plates 91 and 92, is then insertedbetween mandibular bone segments 110 and 120. Bone screws can then beinserted into the openings in self-retaining plates 91 and 92.

Mandibular distraction osteogenesis device 93 then may be activated byinserting an allen wrench 102 into an allen wrench opening 101 in palateexpander 90, as seen in FIG. 16b. One full clockwise rotation of theactivation allen wrench opening 101 equals 0.2 mm of expansion. Apressure can then be produced, forcing extending components 90a and 90bfrom palate expander 90, thus displacing mandibular bone segment 110from mandibular bone segment 120. The allen wrench opening 101 of palateexpander 90 may be accessed through the mouth or an opening on the face.

As described above, the submergible mandibular distraction osteogenesisdevice 93 may be activated using a maximum pressure rate, rather thanthe conventional activation rate. Similarly, mandibular distractionosteogenesis device 93 offers the advantages described above in regardto the zygomatic and alveolar distraction osteogenesis devices.

The foregoing description of the preferred embodiments of the presentinvention has been provided for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Obviously, many modificationsand variations will be apparent to practitioners skilled in the art. Theembodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, therebyenabling others skilled in the art to understand the invention forvarious embodiments and with the various modifications as are suited tothe particular use contemplated. It is intended that the scope of theinvention be defined by the following claims and their equivalents.

What is claimed is:
 1. A submergible device for distracting a firstsegment of a mandibular bone from a second segment of a mandibular boneto allow for bone generation, comprising:(a) a first U-shaped member forcoupling to the first segment of the mandibular bone; (b) a secondU-shaped member for coupling to the second segment of the mandibularbone; (c) a palate expander having a first and second pair of rods,wherein the first and second pair of rods are coupled to the firstU-shaped member and the second U-shaped member, respectively;and,wherein the palate expander transfers a force against the first andsecond U-shaped members, creating a distance between the first andsecond mandibular bone segments.
 2. The submergible device of claim 1,wherein the force is transferred substantially through the first andsecond U-shaped members.
 3. The submergible device of claim 1, whereinthe first U-shaped member, the second U-shaped member, the palateexpander, and the first and second pair of rods consist of stainlesssteel.
 4. The submergible device of claim 1, wherein the first U-shapedmember and the second U-shaped member have a plurality of openings forinserting screws which position the first U-shaped member and the secondU-shaped member to the respective first segment of the mandibular boneand the second segment of the mandibular bone.
 5. The submergible deviceof claim 4, wherein the plurality of screws do not transfer asubstantial amount of the force.
 6. The submergible device of claim 1,wherein the palate expander which transfers a force is activated by anallen wrench.
 7. The submergible device of claim 6, wherein the palateexpander includes a hole for insertion of the allen wrench.
 8. Thesubmergible device of claim 7, wherein turning one full clockwiserotation of the allen wrench equals approximately 0.2 mm of expansion.9. The submergible device of claim 1, wherein the first U-shaped memberand the second U-shaped member include protruding edges having openingsfor receiving the first and second pairs of rods therethrough.
 10. Thesubmergible device of claim 1, wherein the palate expander transfers theforce generating a maximum pressure in order to achieve a maximumdistance.
 11. The submergible device of claim 1, wherein a substantialamount of pressure is exerted at a first platform of the first U-shapedmember.
 12. A method for forming mandibular bone, comprising the stepsof:(a) cutting the mandibular bone into first and second segments; (b)coupling a first member to a palate expander; (c) coupling a secondmember to the palate expander; (d) positioning the palate expanderbetween the first and second segments; (e) securing the first and secondmembers to the first and second segments of the mandibular bone,respectively; and (f) activating the palate expander in order todisplace the first segment of the mandibular bone from the secondsegment of the mandibular bone.